Automatic wire bonders are used during semiconductor assembly and packaging for making electrical wire connections between electrical contact pads on a die and a substrate, or between electrical contact pads on different dice. Wire is fed from a wire spool containing bonding wire, typically gold or copper wire, to a bonding tool such as a capillary for performing wire bonding at the bonding tool.
Along the feeding route of the wire between the wire spool and the capillary, the wire passes through various devices, which may include a pneumatic device and a wire clamp for controlling feeding of the wire during wire bonding. FIG. 1 is a side view of a wire feeding route of a conventional wire bonder. Bonding wire 100, for instance gold or copper wire, is fed from a wire spool (not shown) into a pneumatic device 102 which is operative to apply vertical vacuum suction forces upwards or downwards to urge movement of the bonding wire 100 in these directions. A wire guider 104 is located some distance away from the pneumatic device 102 and it has a small hole for threading and guiding the bonding wire 100 along the feeding route. A wire clamp 106 is located below the wire guider 104 to clamp onto the bonding wire 100 when movement of the bonding wire 100 is to be restrained. The bonding wire 100 is then passed through a capillary 108 located at one end of a transducer horn 110. Wire bonding is conducted at a bottom tip of the capillary 108.
A shortcoming of such a conventional wire bonder design is that wire threading has to be conducted manually when the bonding wire is being set up for wire bonding. Due to the small dimensions of the bonding wire and devices it has to be threaded through, a skilled technician is required to perform manual wire threading, and even then, the process itself is a time-consuming one.
Moreover, broken wire may occur during wire bonding due to various reasons, such as short tail arising from premature termination of a tail bond, missing ball leading to incorrect formation of a ball bond, and other reasons. Each time there is a broken wire, the wire bonder needs to be stopped and the bonding wire has to be rethreaded manually again, thereby incurring unnecessarily long downtimes and incurring penalties in terms of productivity.